This invention relates to roll over protective structures and falling object protective structures which are desirable and in many instances mandatory on farm, industrial, lawn, and utility tractors, earth moving equipment and other operator controlled vehicles where the operator is exposed to injury from such things as vehicle upset, roll over, penetration of the operator's working zone by falling objects such as steel work, trees, rocks, etc. More specifically the invention is concerned with roll over and falling object protective structures that have added strength and durability through the use of interlocking structural members which are welded together after positioning.
In light of the ever increasing awareness of the advantages of providing a zone of safety for exposed vehicle operators the unexpected result discovered through the interlocking of the roll over protective structure's structural members provides greater margins of safety and structural performance.
There are many types and configurations of roll over and falling object protective structures now in use on an extensive range of tractors and earth moving equipment. Roll over structures are usually of a multiple upright post design having connecting members between the upright posts. The structure framework on most current designs is assembled from either round, square, channel or tapered metal tubing. These structures are usually butt welded together at joints and, where necessary, gusseted for added strength.
Falling object structures generally are constructed using the framework of roll over protective structures with the inclusion of a perforated or solid metal plate that fits over the top of the supporting framework.
The upright posts or supports of roll over protective structures are usually fixedly attached to sturdy components of the tractor or vehicles such as axle housings, main frame sections or specially constructed support mounts. Assembly members connect the posts to one another in a manner that is designed to give the structure rigidity.
Upon vehicle upset the roll over protective structures will be subject to forces that will eminate from the upper parts of the structure as this area will be the first to make contact with the ground (or with falling objects). In design configuration the members that tie together the upright posts of the structure will tend to distribute initial load throughout the structure. The process of channeling impact stresses can impose severe forces on fabrication welds at the fixed joints of the roll over or falling object protective structure. As a matter of research it has been observed that in order to minimize the possibility of a protective device failure extensive gusseting and reinforcement of the structure has been necessary.
The invention disclosed here has shown that a very rigid structure can be fabricated with excellent results through the interlocking of structural support members. This is accomplished by fabricating a roll over protective structure with the upright posts of a square tube having four wall surfaces and the horizontal connecting members which may be oriented either perpendicularly or parallel to the longitudinal centerline of the vehicle, of a similar square tube only having an interior dimension approximately equal to the exterior dimension of the upright posts.
By assembling the structure in this manner there is a gusseted effect formed between the the larger section posts and the connecting frame member. After these members have been assembled together they can be welded at the joints that are a consequence of their different but complementary dimensions. The effect of the flat surface interior of the transverse members in relationship to the flat exterior surface of the vertical post members has the effect of an instant gusset. This means, of course, that there exists no need to fabricate an exterior ancillary gusset for this structure joint.
This particular improvement over roll over and falling object protective structures permits the structure to transfer energy without giving rise to weld failures that would cause structure deformation which would be injurious to the vehicle operator positioned within the protective structure.
In the embodiment of the present invention it is also proposed that the upright posts could be of larger internal dimensions than the horizontal connecting members and thus fit around the post connecting members. Also rectangular shaped metal tubing and various combinations of channel section components are anticipated.
Accordingly it is amongst the primary objects of this invention to provide a roll over and falling object protective structure for use on tractors that will reasonably protect the vehicle operator in dire situations such as upset, roll over and exposure to falling objects.
Another object of the invention to to provide a method of roll over protective structure fabrication that adopts itself to good welding.
Many of the present roll over protective structure configurations provide adequate strength, however, the quantity of steel work, the need of extreme care to machine surfaces such that good weldments can be made and the attendant high fabrication costs make these structures less desirable in light of the instant invention. Many of the structural components do not require close machine work as is needed when butt welding similar non-interlocked structures together. All that need be done here is to cut out one member of the interlocking structure on a bias angle and the other on either a complementary angle or a straight angle. After fitting these components together there is formed a ledge between components that provides an excellent weld bed.
Consequently, it is also an object of the invention to enable roll over protective structures to be fabricated at less expense than is presently incurred.
A further object of the invention is to minimize the amount of preparatory machining of component structural members.